Error when I am using MPI run on multi-cores.

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1

Hello,

Our lab is planning to buy a new computer with 2 processors and 12 cores in each. So we send a request to the computer manufacture to have a benchmark computing. I specify the Processor in the input file by using

Processors 2 3 2

And using the command line “mpiexec -np 12” to run the program. But it returned

[email protected]...:/benchmark$ mpiexec -np 12 ./lmp_mpi <in.C.10w >out.C.10w
[email protected]...:/benchmark$ cat out.C.10w
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
ERROR: Specified processors != physical processors (../comm.cpp:287)

2

Hello,

Our lab is planning to buy a new computer with 2 processors and 12 cores
in each. So we send a request to the computer manufacture to have a
benchmark computing. I specify the Processor in the input file by using

Processors 2 3 2

And using the command line “mpiexec -np 12” to run the program. But it
returned

[email protected]...:/benchmark$ mpiexec -np 12 ./lmp_mpi <in.C.10w >out.C.10w
[email protected]...:/benchmark$ cat out.C.10w
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
LAMMPS (10 Aug 2015)
​​
LAMMPS (10 Aug 2015)
ERROR: Specified processors != physical processors (../comm.cpp:287)
———————————————————————————

We have used our 4-core computer doing the same thing without problems
before. So can anyone tell me where this error comes from?

​you should have only one line of​ "
​
LAMMPS (10 Aug 2015)" in your output.
the fact that you are getting more is an indication that you are running
either a serial binary or that your mpiexec command is from a different MPI
library than what the binary was compiled with. thus mpiexec will not
launch one parallel job with 12 ranks, but 12 serial jobs with 1 rank each.
the error message then comes from processors command, as only 1 processor
on the same communicator is available for each instance, yet your command
requires 12.

​axel.​